Both players satisfy the necessary criteria, and Home Office rules allow for an extension of at least another three years to a UK Tier 2 [Sportsperson] visa.

The players are required to apply for their visas in person, with each application requiring a valid certificate of sponsorship from their new respective club, along with the endorsement of the Football Association.

Sanchez fulfils all necessary criteria and is expected to be issued an extension without complication

The Home Office will not discuss individual cases but Sky Sports News understands neither player will have to leave the UK in order to meet any extension requirements.

With Mkhitaryan representing and captaining Armenia - ranked 90th in the world by FIFA - specific criteria is required in order for a permit extension to be granted.

James Cooper explains why Alexis Sanchez will need a work permit before he can complete a move to Manchester United

James Cooper explains why Alexis Sanchez will need a work permit before he can complete a move to Manchester United

Necessary factors include the elite status of the league, the value of the transfer and the value of the agreed weekly wages.

European and domestic appearances are also taken into account, all of which Mkhitaryan is expected to fulfil and extend his existing permit.

The playmaker has played 15 times in the Premier League this season for United, coming up with one goal in the process.

Mkhitaryan will also have to meet additional criteria to obtain the extension

Mkhitaryan has also featured four times in the Champions League, again scoring one goal.

Both United and Arsenal are expected to get clearance for their new players straight away, though could announce the signings beforehand 'subject to obtaining a work permit'.

Mkhitaryan would be cup-tied for Arsenal's Carabao Cup semi-final second leg against Chelsea on Wednesday, though Sanchez would be available to feature in United's FA Cup fourth-round fixture with Yeovil on Friday, provided the deal is completed and he is registered as a United player before 12pm on Friday.